Method of producing a wavelength-converting casting composition

ABSTRACT

The wavelength-converting casting composition is based on a transparent epoxy casting resin with a luminous substance admixed. The composition is used in an electroluminescent component having a body that emits ultraviolet, blue or green light. An inorganic luminous substance pigment powder with luminous substance pigments is dispersed in the transparent epoxy casting resin. The luminous substance is a phosphorous group of the general formula A 3 B 5 X 12 :M, and the luminous substance pigments have particle sizes ≦20 μm and a mean grain diameter d 50 ≦5 μm.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of U.S. patent application Ser. No. 09/536,564, datedMar. 28, 2000, now U.S. Pat. No. 6,277,301, which is a division of U.S.application Ser. No. 09/082,205, filed May 20, 1998, now U.S. Pat. No.6,066,861, which was a continuation of copending internationalapplication PCT/DE97/02139, filed Sep. 22, 1997, which designated theUnited States.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a wavelength-converting casting compositionbased on a transparent epoxy casting resin which is mixed with aluminous substance, for an electroluminescent component having a bodythat emits ultraviolet, blue or green light.

2. Description of the Related Art

A component of that type has become known, for instance, from Germanpublished, non-prosecuted patent application DE 38 04 293. The referencedescribes an arrangement with an electroluminescent diode or laserdiode, in which the emissions spectrum emitted by the diode is shiftedtoward longer wavelengths, by means of a plastic element mixed with afluorescing, light-converting, organic colorant. The light emitted bythe arrangement as a result has a different color from what the lightemitting diode emitted. Depending on the type of colorant added to theplastic, it is possible to produce LED arrays that light up in differentcolors with one and the same type of light-emitting diode (LED).

In many potential applications for LEDs, such as in display elements inmotor vehicle dashboards, illumination in aircraft and automobiles, andin LED displays capable of showing full color, there is an increasingdemand for LED arrays with which mixed color light and in particularwhite light can be generated.

However, the prior art casting compositions of the type referred to atthe outset with organic luminous substances exhibit a shift in the colorlocation, that is, the color of the light emitted by theelectroluminescent component, under temperature and temperature/humiditystresses.

Japanese patent disclosure JP-07 176 794-A describes awhite-light-emitting planar light source, in which two diodes that emitblue light are disposed on one face end of a transparent plate and emitlight into the transparent plate. The transparent plate is coated on oneof the two opposed main sides with a fluorescing substance that emitslight when it is excited with the blue light of the diodes. The lightemitted by the fluorescing substance has a different wavelength from theblue light emitted by the diodes. In this known component, it isespecially difficult to apply the fluorescing substance in such a waythat the light source emits homogeneous white light. Moreover,replicability and mass production presents major problems, because evenslight fluctuations in the layer thickness of the fluorescing layer, forinstance from irregularities of the surface of the transparent plate,cause a change in the white of the light emitted.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide awavelength-converting casting mass, which overcomes the above-mentioneddisadvantages of the prior art devices and methods of this general typeand with which electroluminescent components can be produced that emithomogeneous mixed-colored light, and which enables mass production atreasonable engineering effort and expense and with maximally replicablecomponent characteristics. The emitted light should be color-stable evenunder temperature and temperature/humidity stresses. It is a furtherobject to specify a use for the casting mass and a method for producingthe composition.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a wavelength-converting castingcomposition, for converting a wavelength of ultraviolet, blue or greenlight emitted by an electro-luminescent component, comprising:

a transparent epoxy casting resin;

an inorganic luminous substance pigment powder dispersed in thetransparent epoxy resin, the pigment powder comprising luminoussubstance pigments from a phosphorus group having the general formulaA₃B₅X₁₂:M;

the luminous substance pigments having grain sizes ≦20 μm and a meangrain diameter d₅₀≦5 μm.

In accordance with an added feature of the invention, the mean graindiameter d₅₀ of the luminous substance pigments is between one and twomicrometers.

Inorganic/mineral luminous substances are extremely stable with regardto temperature and temperature/humidity stresses.

In accordance with an additional feature of the invention, thecomposition includes the following parts:

a) epoxy casting resin ≦60% by weight;

b) luminous substance pigments >0 and ≦25% by weight;

c) thixotropic agent >0 and ≦10% by weight;

d) mineral diffusor >0 and ≦10% by weight;

e) processing adjuvant >0 and ≦3% by weight;

f) hydrophobic agent >0 and ≦3% by weight; and

g) adhesion promoters >0 and ≦2% by weight.

Suitable epoxy casting resins are described for instance in Germanpublished, non-prosecuted patent application 26 42 465 (pp. 4–9, inparticular examples 1–4), and in European patent disclosure EP 0 039 017and U.S. Pat. No. 4,365,052 (pp. 2–5, in particular examples 1–8appearing in both the EP and U.S. patents). The disclosures of thosedocuments are hereby expressly incorporated by reference.

Pyrogenic silicic acid is for instance used as the thixotropic agent.The thixotropic agent is used to thicken the epoxy casting resin, so asto reduce the sedimentation of the luminous substance pigment powder.The flow and wetting properties are also adjusted for processing thecasting resin

CaF₂ is preferably used as a mineral diffusor for optimizing theluminous pattern of the component.

Glycol ether is for instance suitable as a processing adjuvant. Itimproves the compatibility between the epoxy casting resin and theluminous substance pigment powder and is thus used to stabilize thedispersion of luminous substance pigment powder and epoxy casting resin.To that end, surface modifiers based on silicone can also be employed.

The hydrophobic agent, such as liquid silicone wax, is also used tomodify the pigment surface; in particular, the compatibility andwettability of the inorganic pigment surface is improved with theorganic resin.

The adhesion promoter, such as functional alkoxysiloxane, improves theadhesion between the pigments and the epoxy resin in the cured state ofthe casting composition. As a result it is attained that the boundaryface between the epoxy resin and the pigments will not rupture, forinstance in response to temperature fluctuations. Gaps between the epoxyresin and the pigments would cause light losses in the component.

The epoxy casting resin, preferably with a reactive triple oxiran ring,preferably includes a monofunctional and/or multifunctional epoxycasting resin system (≧80% by weight, such as bisphenol-A-diglycidylether), a reactive diluent (≦10% by weight, such as aromaticmonoglycidyl ether), a multifunctional alcohol (≦5% by weight), adegassing agent based on silicone (≦1% by weight), and a decolorizingcomponent to adjust the color number (≦1% by weight).

In accordance with another feature of the invention, the luminoussubstance pigments are substantially spherical particles or flakelikeparticles. The tendency to clumping of such pigments is advantageouslyvery slight. The H₂O content is below 2%.

In the production and processing of epoxy casting resin components withinorganic luminous substance pigment powders, in general not onlywetting but also sedimentation problems occur. Especially luminoussubstance pigment powders with d₅₀≦5 μl have a strong tendency toclumping. In the last-named composition of the casting composition, theluminous substance pigments, with the above-indicated particle size, canadvantageously be substantially free of clumps and can be dispersedhomogeneously in the epoxy casting resin. This dispersion is stable evenunder long-term storage of the casting composition. Essentially noproblems of wetting and/or sedimentation occur.

In accordance with a further feature of the invention, the luminoussubstance pigments are particles of Ce-doped garnets, such as,particularly, YAG:Ce particles. An advantageous dopant concentration is1%, for example, and an advantageous luminous substance concentration is12%, for example. The preferred high-purity luminous substance pigmentpowder also advantageously has an iron content of ≦5 ppm. A high ironcontent leads to high light losses in the component. The luminoussubstance pigment powder is highly abrasive. The iron content in thecasting composition can therefore rise considerably during production.Iron contents in the casting composition <20 ppm are advantageous.

The inorganic luminous substance YAG:Ce has the particular advantage,among others, that is involves insoluble color pigments with an index ofrefraction of approximately 1.84. As a result, along with the wavelengthconversion, dispersion and scattering effects occur that lead to goodmixing of blue diode emissions with yellow converter radiation.

It is also especially advantageous that the luminous substanceconcentration in the epoxy resin when inorganic luminous substancepigments are used is not limited by the solubility, as is the case fororganic colorants.

For further reduction of clumping, the luminous substance pigments mayadvantageously be provided with a silicone coating.

With the above and other objects in view there is also provided, inaccordance with the invention, a method of producing awavelength-converting casting composition, for converting a wavelengthof ultraviolet, blue or green light emitted by an electroluminescentcomponent, the method which comprises:

providing a base of transparent epoxy casting resin;

providing a luminous substance pigment powder of luminous substancepigments from a phosphorus group having the general formula A₃B₅X₁₂:M;tempering the luminous substance pigment powder at a temperature of≦200° C. and subsequently mixing the tempered pigment powder with theepoxy casting resin.

Tempering is preferably effected for approximately ten hours. As aresult, again the tendency to clumping can be reduced.

As an alternative or in addition for this purpose, the luminoussubstance pigment powder, before being mixed with the epoxy castingresin, can be slurried in a high-boiling point alcohol and subsequentlydried. A further possibility for reducing clumping is to add ahydrophobic silicone wax to the luminous substance pigment powder beforethe powder is mixed with the epoxy casting resin. Surface stabilizationof the phosphors by heating the pigments in the presence of glycolethers, for instance for 16 hours at T>60° C., is especiallyadvantageous.

To avoid problematic contamination upon dispersal of the luminoussubstance pigments, caused by abrasion, reaction vessels, agitators anddispersing devices as well as rolling mechanisms of glass, corundum,carbide and nitride materials as well as especially hardened types ofsteel are used. Clump-free luminous substance dispersions are alsoobtained by ultrasonic methods or by the use of screens and glassceramic frits.

An especially preferred inorganic luminous substance for producingoptoelectronic components that light up white is the phosphorous YAG:Ce(Y₃Al₅O₁₂:Ce³⁻). This phosphorous can be especially simply mixed withtransparent epoxy casting resins conventionally used in LED technology.Also conceivable as luminous substances are other garnets, doped withrare earths, such as Y₃Ga₅O₁₂:Ce³⁻, Y(Al, Ga)₅O₁₂:Ce³⁻, and Y(Al,Ga)₅O₁₂:Tb³⁻.

To generate mixed-colored light, the thiogallates doped with rare earthsare moreover especially suitable, examples being CaGa₂S₄:Ce³⁻ andSrGa₂S₅:Ce³⁻. Once again, the use of aluminates doped with rare earths,such as YAlO₃:Ce³⁻, YGaO₃:Ce³⁻, Y(Al, Ga)O₃:Ce³⁻, and orthosilicatesdoped with rare earths, M₂SiO₅:Ce³⁻, (M:Sc,Y,Sc), such as Y₂SiO₅:Ce³⁻ isconceivable. In all the yttrium compounds, the yttrium can in principlealso be replaced with scandium or lanthanum.

Therefore, in the phosphorus group A₃B₅X₁₂:M, the variables may standfor the following exemplary elements: A═Y, Ca, Sr; B═Al, Ga, Si; X═O, S;and M═Ce³⁺, Tb³⁺. The variables can represent a single one of the listedexemplary elements. Alternatively, the variables can represent a mixtureof two or more of the listed exemplary elements.

Preferably, the casting composition according to the invention is usedin a radiation-emitting semiconductor body, in particular with an activesemiconductor layer or semiconductor layer sequence of Ga_(x)In_(1-x)Nor Ga_(x)Al_(1-x)N, which in operation emits an electromagneticradiation of the ultraviolet, blue and/or green spectral range. Theluminous substance particles in the casting composition convert some ofthe radiation originating in this spectral range into radiation with alonger wavelength, in such a way that the semiconductor component emitsmixed radiation, and in particular mixed-colored light comprising thisradiation as well as radiation from the ultraviolet, blue and/or greenspectral range. This means for instance that the luminous substanceparticles spectrally selectively absorb some of the radiation emitted bythe semiconductor body and emit in the longer-wave range. Preferably,the radiation emitted by the semiconductor body has a relative maximumintensity at a wavelength lambda λ≦520 nm, and the wavelength rangespectrally selectively absorbed by the luminous substance particles isoutside this maximum intensity.

It is also advantageously possible for a plurality of different kinds ofluminous substance particles, which emit at different wavelengths, to bedispersed in the casting composition. This is preferably achieved bymeans of different doping in different host lattices. Thisadvantageously makes it possible to generate manifold color mixtures andcolor temperatures of the light emitted by the component. This isespecially of interest for LEDs capable of emitting full color.

In a preferred use of the casting composition of the invention, aradiation-emitting semiconductor body (such as an LED chip) is at leastpartly enclosed by the casting composition. The casting composition ispreferably simultaneously used as a component envelope (housing). Theadvantage of a semiconductor component in accordance with thisembodiment is essentially that conventional production lines used tomake conventional LEDs (such as radial LEDs) can be used to produce it.For the component envelope, instead of the transparent plastic used forthis purpose in conventional LEDs, the casting composition can simply beemployed.

With the casting composition of the invention, it is possible in asimple way, with a single colored light source, particularly an LED witha single semiconductor body that emits blue light, to createmixed-colored and in particular white light. For instance to generatewhite light with a semiconductor body that emits blue light, some of theradiation emitted by the semiconductor body is converted out of the bluespectral range into the yellow spectral range, which is complementary incolor to blue, by means of inorganic luminous substance particles.

The color temperature or color location of the white light can be variedby a suitable choice of the luminous substance, its particle size, andits concentration. In addition, luminous substance mixtures can also beemployed, and as a result advantageously the desired tonality of thecolor of the emitted light can be adjusted very precisely.

Especially preferably, the casting composition is used in aradiation-emitting semiconductor body in which the emitted radiationspectrum has a maximum intensity at a wavelength between 420 nm and 460nm, and in particular at 430 nm (examples being semiconductor bodiesbased on Ga_(x)Al_(1-x)N) or 450 nm (such as semiconductor bodies basedon Ga_(x)In_(1-x)N). With such a semiconductor component, nearly all thecolors and mixed colors in the CIE chromaticity diagram canadvantageously be generated.

Instead of the radiation-emitting semiconductor body ofelectroluminescing semiconductor material, however, some otherelectroluminescing material may be used, such as polymer material.

With the objects of the invention is view there is further provided, inaccordance with the invention, a light-emitting semiconductor component,comprising:

a semiconductor body formed of a semiconductor layer sequence and beingcapable, during an operation of the semiconductor component, of emittingelectromagnetic radiation in at least one of an ultraviolet, blue, andgreen spectral range;

a wavelength-converting casting composition disposed in a vicinity ofthe semiconductor body, the casting composition being formed of atransparent epoxy casting resin and an inorganic luminous substancepigment powder dispersed in the transparent epoxy resin, the pigmentpower comprising luminous substance pigments from a phosphorus grouphaving the general formula A₃B₅X₁₂:M and having grain sizes ≦20 μm and amean grain diameter d₅₀≦5 μm;

the luminous substance pigments converting a portion of the radiationoriginating from the ultraviolet, blue and green spectral range intoradiation of a higher wavelength, such that the semiconductor componentemits mixed radiation including the higher-wavelength radiation andradiation from at least one of the ultraviolet, blue and green spectralrange.

In other words, the casting composition is especially suitable for alight-emitting semiconductor component (for instance an LED), in whichthe electroluminescing semiconductor body is disposed in a recess of aprefabricated housing, optionally already provided with a leadframe, andthe recess is provided with the casting composition. This kind ofsemiconductor component can be produced in great numbers on conventionalproduction lines. All that is needed, after mounting of thesemiconductor body in the housing, is to fill the recess with thecasting composition.

A semiconductor component that emits white light can be produced withthe casting composition according to the invention advantageously bychoosing the luminous substance in such a way that a blue radiationemitted by the semiconductor body is converted into complementarywavelength ranges, in particular blue and yellow, or additive colortriads, such as blue, green and red. The yellow or green and red lightis generated via the luminous substances. The color tonality (colorlocation in the CIE chromaticity diagram) of the white light thusproduced can then be varied by means of a suitable choice of theluminous substance or luminous substances in terms of their mixture andconcentration.

To improve the mixing of the radiation emitted by an electroluminescingsemiconductor body with the radiation converted by the luminoussubstance and thus to improve the homogeneity of color of the lightemitted by the component, in an advantageous feature of the castingcomposition according to the invention a blue-luminescing colorant,which attenuates a so-called directional characteristic of the radiationemitted by the semiconductor body. The term “directional characteristic”is understood to mean that the radiation emitted by the semiconductorbody has a preferential emission direction.

A semiconductor component according to the invention that emits whitelight, with an electroluminescing semiconductor body emitting bluelight, can be especially preferably achieved by admixing the inorganicluminous substance YAG:Ce (Y₃Al₅O₁₂:Ce³⁺) with the epoxy resin used forthe casting composition. Some of the blue radiation emitted by thesemiconductor body is shifted by the inorganic luminous substance(Y₃Al₅O₁₂Ce³⁻) into the yellow spectral range and thus into a wavelengthrange that is complementary in color to the color blue. The colortonality (color location in the CIE chromaticity diagram) of the whitelight can then be varied by means of a suitable choice of the colorantconcentration.

In addition, light-scattering particles, so-called diffusers, can beadded to the casting composition. As a result, the color impression andthe emission characteristics of the semiconductor component canadvantageously be still further optimized.

With the casting composition of the invention, advantageously anultraviolet radiation emitted by an electroluminescing semiconductorbody along with the visible radiation can advantageously be convertedinto visible light. This markedly increases the brightness of the lightemitted by the semiconductor body.

A particular advantage of semiconductor components according to theinvention that emit white light, and in which YAG:Ce is used inparticular as the luminescence-converting colorant, is that thisluminous substance on excitation with blue light causes a spectral shiftof approximately 100 nm between absorption and emission. This leads to asubstantial reduction and reabsorption of the light emitted by theluminous substance and thus to a higher light yield. Moreover, YAG:Ceadvantageously has high thermal and photochemical (such as UV) stability(substantially higher than organic luminous substances) so that evenwhite-emitting diodes for outdoor use and/or high temperature ranges canbe produced.

YAG:Ce has by now proved itself to be the best-suitable luminoussubstance in terms of reabsorption, light yield, thermal andphotochemical stability, and processability. However, the use of otherCe-doped phosphors, in particular Ce-doped types of garnet, is alsoconceivable.

The wavelength conversion of the primary radiation is determined by thecrystal field cleavage of the active transition metal centers in thehost lattice. By substituting Gd and/or Lu for Y, or Ga for Al in theY₃Al₅O₁₂ garnet lattice, the emission wavelengths can be shifted invarious ways, and this can also be done by the type of doping. Bysubstituting Eu³⁺ and/or Cr³⁺ for Ce³⁺ centers, corresponding shifts canbe brought about. Corresponding dopings with Nd³⁺ and Er³⁺, even make itpossible, because of the greater ion radii and thus reduced crystalfield cleavage, to make components that emit infrared (IR) light.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a wavelength converting casting composition, its use, and method forits production, it is nevertheless not intended to be limited to thedetails shown, since various modifications and structural changes may bemade therein without departing from the spirit of the invention andwithin the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a first semiconductor componentwith a casting composition according to the invention;

FIG. 2 is a schematic sectional view of a second semiconductor componentwith a casting composition according to the invention;

FIG. 3 is a schematic sectional view of a third semiconductor componentwith a casting composition according to the invention;

FIG. 4 is a schematic sectional view of a fourth semiconductor componentwith a casting composition according to the invention;

FIG. 5 is a schematic sectional view of a fifth semiconductor componentwith a casting composition according to the invention;

FIG. 6 is a graph of an emission spectrum of a semiconductor body thatemits blue light, with a layer sequence on the basis of GaN;

FIG. 7 is a graph of the emissions spectra of two semiconductorcomponents with a casting composition according to the invention, whichemit white light; and

FIG. 8 is a graph of the emissions spectra of further semiconductorcomponents that emit white light.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is now had to the figures of the drawing in which elementsthat are identical or that function identically are identified by thesame reference numerals throughout.

In the light-emitting semiconductor component of FIG. 1, thesemiconductor body 1 is secured by its back-side contact 11 to a firstelectrical terminal 2 by means of an electrically conductive joiningmeans such as a metal solder or an adhesive. The front-side contact 12is joined to a second electrical terminal 3 by means of a bond wire 14.

The free surfaces of the semiconductor body 1 and portions of theelectrical terminals 2 and 3 are enclosed directly by a hardened,wavelength-converting casting or potting composition 5. The castingcomposition preferably has the following: epoxy casting resin 80 to 90%by weight, luminous substance pigments (YAG:Ce)≦15% by weight,diethylene glycol monomethyl ether ≦2% by weight, Tegopren 6875-45 (aprocessing adjustment, an additive for keeping the surface of the resinfree from bubbles, craters and similar faults)≦2% by weight, Aerosil 200(a thixotropic agent)≦5% by weight.

The exemplary embodiment of a semiconductor component according to theinvention shown in FIG. 2 differs from that of FIG. 1 in that thesemiconductor body 1 in portions of the electrical terminals 2 and 3 areenclosed not by a wavelength-converting potting mass but by atransparent envelope 15. The transparent envelope 15 does not cause anychange in the wavelength of the radiation emitted by the semiconductorbody 1 and for instance comprises an epoxy, silicone or acrylate resinconventionally used in LED technology, or some other suitableradiation-permeable material, such as inorganic glass.

A layer 4 is applied to the transparent envelope 15. The layer 4comprises a wavelength-converting casting composition and, as shown inFIG. 2, covers the entire surface of the envelope 15. It is equallyconceivable for the layer 4 to cover only a portion of the surface. Thelayer 4 for instance comprises a transparent epoxy resin which is mixedwith luminous substance particles 6. Once again, for a semiconductorcomponent that emits white light, YAG:Ce is preferred as the luminoussubstance.

FIG. 3 illustrates a particularly advantageous and preferred embodimentof the invention. The first and second electrical terminals 2, 3 areembedded in an opaque, and optionally prefabricated, basic housing 8that has a recess 9. The term “prefabricated” is understood to mean thatthe basic housing 8 is already finished at the terminals 2, 3, forinstance by means of injection molding, before the semiconductor body ismounted on the terminal 2. The basic housing 8, by way of example, isformed of opaque plastic, and in terms of its form the recess 9 isembodied as a reflector 17 for the radiation emitted by thesemiconductor body in operation (the reflection optionally beingachieved by means of suitable coating of the inside walls of the recess9). Such basic housings 8 are used in particular for LEDs that aresurface-mounted on printed circuit boards. They are applied, beforemounting of the semiconductor body, to a conductor strip (lead frame)that has the electrical terminals 2, 3, the application for instancebeing done by injection molding.

The recess 9 is filled with a casting composition 5, whose compositionis equivalent to that given above in conjunction with the description ofFIG. 1.

FIG. 4 shows a so-called radial diode. Here, the electroluminescingsemiconductor body 1 is secured, for instance by soldering or adhesivebonding, in a part 16, embodied as a reflector, of the first electricalterminal 2. Such housing constructions are known in LED technology andtherefore require no further description here. The free surfaces of thesemiconductor body 1 are covered directly by a casting composition 5containing luminous substance particles 6, and the casting compositionin turn is surrounded by a further transparent housing envelope 10.

It will be appreciated by those skilled in the art that, in theconstruction of FIG. 4 as well, analogously to the component of FIG. 1,an integral envelope comprising hardened casting composition 5 withluminous substance particles 6, may also be used.

In the exemplary embodiment of FIG. 5, a layer 4 (see the list ofmaterials given above) is coated directly on the semiconductor body 1.The semiconductor body 1 and portions of the electrical terminals 2, 3are enclosed by a further transparent housing envelope 10. The lattercauses no change in wavelength of the radiation that has passed throughthe layer 4, and it is made for instance from a transparent epoxy resinthat is usable in LED technology, or from glass.

Such semiconductor bodies 1 provided with a layer 4 and without anenvelope can naturally advantageously be used in all the housingconstructions known from LED technology (such as SMD housings, andradial housings; see FIG. 4).

In all the components described above, in order to optimize the colorimpression of the light emitted and to adapt the emissioncharacteristics, the casting composition 5, optionally the transparentenvelope 15, and/or optionally the further transparent envelope 10 mayhave light-scattering particles, advantageously so-called diffusers.Examples of such diffusers are mineral fillers, in particular CaF₂,TiO₂, SiO₂, CaCO₃, or BaSO₄, or organic pigments. These materials caneasily be added to epoxy resins.

FIGS. 6–8 illustrate emissions spectra. FIG. 6 refers to a semiconductorbody that emits blue light (luminescence maximum at λ˜430 nm) and FIGS.7 and 8 refer to semiconductor components that emit white light. In eachcase, the wavelength λ is plotted in nm on the abscissa, and a relativeelectroluminescence (EL) intensity is plotted on the ordinate.

Of the radiation emitted by the semiconductor body in FIG. 6, only someis converted into a longer-wavelength range, so that white light iscreated as the mixed color. The dashed line 30 in FIG. 7 represents anemissions spectrum of a semiconductor component which emits radiationcomprising two complementary wavelength ranges (blue and yellow) andthus emits combined white light. The emissions spectrum here has onemaximum each at wavelengths between approximately 400 and approximately430 nm (blue) and between approximately 550 and 580 nm (yellow). Thesolid line 31 represents the emissions spectrum of a semiconductorcomponent that mixes the color white from three wavelength ranges(additive color triad comprising blue, green and red). The emissionsspectrum here has one maximum each for the wavelengths of approximately430 nm (blue), approximately 500 nm (green) and approximately 615 nm(red).

FIG. 8 shows an emissions spectrum of a white-emitting semiconductorcomponent, which is provided with a semiconductor body that transmits anemissions spectrum as shown in FIG. 6 and in which YAG:Ce is used as theluminous substance. Of the radiation shown in FIG. 6 emitted by thesemiconductor body, only some is converted into a longer-wavelengthrange, so that white light is created as a mixed color. The variouslydashed lines 32—33 of FIG. 8 represent emissions spectra ofsemiconductor components according to the invention, in which the epoxyresin of the casting composition 5 has different YAG:Ce concentrations.Each emissions spectrum has one maximum intensity between lambda=420 nmand lambda=430 nm (i.e., in the blue spectrum), and between lambda=520mm and lambda=545 nm (i.e., in the green 15 spectrum). The emissionbands having the longer-wavelength maximum intensity are predominantlylocated in the yellow spectral range. The graph of FIG. 8 shows that inthe semiconductor component of the invention, the CIE color location ofthe white light can be varied in a simple way by varying the luminoussubstance concentration in the epoxy resin.

While the foregoing specification refers specifically to a semiconductorbody, for example LED chips or laser diode chips, the invention is notin the least restricted to these embodiments. The term may also beunderstood to mean a polymer LED, for instance, that emits an equivalentradiation spectrum.

1. A method of producing a wavelength-converting casting composition forapplication on an ultraviolet, blue or green light emitting body, thewavelength-converting casting composition containing luminous substancepigments having grain sizes ≦20 μm and a mean grain diameter d₅₀≦5 μm,the method which comprises: providing a base of transparent epoxycasting resin; providing the luminous substance pigments from aphosphorus group having the general formula A₃B₅X₁₂:M, where A is atleast one element selected from the group consisting of Y, Gd, Lu, Sc.and La; B is at least one element selected from the group consisting ofAl and Ga; X is oxygen; and M is at least one element selected from thegroup consisting of Ce, Eu, Cr, Nd, Er, and Tb; and mixing the luminoussubstance pigments with the base.
 2. The method according to claim 1,which comprises, prior to the mixing step, slurrying the luminoussubstance pigments in a high-boiling alcohol and subsequently drying theluminous substance pigments.
 3. The method according to claim 1, whichcomprises, prior to the mixing step, adding hydrophobic silicone wax tothe luminous substance pigments.
 4. The method according to claim 1,which comprises surface-modifying the luminous substance pigments atelevated temperatures with alcohols, glycol ethers and silicones.
 5. Amethod of producing a wavelength-converting casting composition forapplication on an ultraviolet, blue or green light emitting body, thewavelength-converting casting composition containing luminous substancepigments having grain sizes ≦20 μm and a mean grain diameter d₅₀≦5 μm,the method which comprises: providing a base of transparent epoxycasting resin; providing the luminous substance pigments selected fromthe group consisting of Ce-doped phosphors; garnets doped with rareearths; thiogallates doped with rare earths; aluminates doped with rareearths; and orthosilicates doped with rare earths; mixing the luminoussubstance pigments with the base; and prior to the mixing step, addinghydrophobic silicone wax to the luminous substance pigments.
 6. A methodof producing a wavelength-converting casting composition for applicationon an ultraviolet, blue or green light emitting body, thewavelength-converting casting containing luminous substance pigmentshaving grain sizes ≦20 μm and a mean grain diameter d₅₀≦5 μm, the methodcomprising: providing a base of transparent epoxy casting resin;providing the luminous substance pigments selected from the groupconsisting of Ce-doped phosphors; garnets doped with rare earths;thiogallates doped with rare earths; aluminates doped with rare earths;and orthosilicates doped with rare earths; mixing the luminous substancepigments with the base; and surface-modifying the luminous substancepigments at elevated temperatures with alcohols, glycol ethers andsilicones.
 7. A method of producing a wavelength-converting castingcomposition for application on an ultraviolet, blue or green lightemitting body component, the wavelength-converting casting compositioncontaining luminous substance pigments having grain sizes ≦20 μm and amean grain diameter d₅₀≦5 μm, the method comprising: providing a base oftransparent epoxy casting resin; providing the luminous substancepigments selected from the group consisting of Ce-doped phosphors;garnets doped with rare earths; thiogallates doped with rare earths;aluminates doped with rare earths; and orthosilicates doped with rareearths; and mixing the luminous substance pigments with the base,wherein the mean grain diameter d₅₀ of the luminous substance pigmentsis between one and two micrometers.
 8. A method of producing awavelength-converting casting composition for application on anultraviolet, blue or green light emitting body, thewavelength-converting casting composition containing luminous substancepigments having grain sizes ≦20 μm and a mean grain diameter d₅₀≦5 μm,the method comprising: providing a base of transparent epoxy castingresin; providing the luminous substance pigments selected from the groupconsisting of Ce-doped phosphors; garnets doped with rare earths;thiogallates doped with rare earths; aluminates doped with rare earths;and orthosilicates doped with rare earths; mixing the luminous substancepigments with the base; and adding light-scattering particles to thecasting composition.
 9. A method of producing a wavelength-convertingcasting composition for application on an ultraviolet, blue or greenlight emitting body, the wavelength-converting casting compositioncontaining luminous substance pigments having grain sizes ≦20 μm and amean grain diameter d₅₀≦5 μm, the method comprising: providing a base oftransparent epoxy casting resin; providing the luminous substancepigments selected from the group consisting of Ce-doped phosphors;garnets doped with rare earths; thiogallates doped with rare earths;aluminates doped with rare earths; and orthosilicates doped with rareearths; and mixing the luminous substance pigments with the base,wherein the casting composition comprises a content of iron ≦20 ppm. 10.A method of producing a wavelength-converting casting compositioncontaining luminous substance pigments having grain sizes ≦20 μm and amean grain diameter d₅₀≦5 μm for a white light emitting semiconductorcomponent having an electroluminescing semiconductor body emitting bluelight, the method comprising: providing a base of transparent epoxycasting resin, providing the luminous substance pigments selected fromthe group consisting of garnets doped with rare earths; thiogallatesdoped with rare earths; aluminates dopes with rare earths; andorthosilicates doped with rare earths: which pigments shift some of theblue light emitted by the semiconductor body into the green and redspectral range; mixing the luminous substance pigments with the base;and prior to the mixing step, slurrying the luminous substance pigmentsin a high-boiling alcohol and subsequently drying the luminous substancepigments.
 11. A method of producing a wavelength-converting castingcomposition containing luminous substance pigments having grain sizes≦20 μm and a mean grain diameter d₅₀≦5 μm for a white light emittingsemiconductor component having an electroluminescing semiconductor bodyemitting blue light, the method comprising: providing a base oftransparent epoxy casting resin, providing the luminous substancepigments selected from the group consisting of garnets doped with rareearths; thiogallates doped with rare earths; aluminates dopes with rareearths; and orthosilicates doped with rare earths: which pigments shiftsome of the blue light emitted by the semiconductor body into the greenand red spectral range; mixing the luminous substance pigments with thebase; and surface-modifying the luminous substance pigments at elevatedtemperatures with alcohols, glycol ethers and silicones.
 12. A method ofproducing a wavelength-converting casting composition containingluminous substance pigments having grain sizes ≦20 μm and a mean graindiameter d₅₀≦5 μm for a white light emitting semiconductor componenthaving an electroluminescing semiconductor body emitting blue light, themethod comprising: providing a base of transparent epoxy casting resin,providing the luminous substance pigments selected from the groupconsisting of garnets doped with rare earths; thiogallates doped withrare earths; aluminates dopes with rare earths; and orthosilicates dopedwith rare earths: which pigments shift some of the blue light emitted bythe semiconductor body into the green and red spectral range; mixing theluminous substance pigments with the base; and prior to the mixing step,adding hydrophobic silicone wax to the luminous substance pigments. 13.A method of producing a wavelength converting casting compositioncontaining luminous substance pigments having grain sizes ≦20 μm and amean grain diameter d₅₀≦5 μm for a white light emitting semiconductorcomponent having an electroluminescing semiconductor body emitting bluelight, the method comprising: providing a base of transparent epoxycasting resin, providing the luminous substance pigments selected fromthe group consisting of garnets doped with rare earths; thiogallatesdoped with rare earths; aluminates dopes with rare earths; andorthosilicates doped with rare earths: which pigments shift some of theblue light emitted by the semiconductor body into the green and redspectral range; and mixing the luminous substance pigments with thebase; and wherein the casting composition comprises a content of iron≦20 ppm.
 14. The method according to claim 1, wherein the mean graindiameter d₅₀ of the luminous substance pigments is between one and twomicrometers.
 15. The method according to claim 1, which comprises addinglight-scattering particles to the casting composition.
 16. The methodaccording to claim 1, wherein the casting composition comprises acontent of iron ≦20 ppm.
 17. The method according to claim 1, whichfurther comprises, prior to the mixing step, tempering the luminoussubstance pigments at a temperature of ≧200° C.